Re: Advice on MyXactMade* flags, MyLastRecPtr, pendingDeletes and lazy XID assignment

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>
Cc: Postgresql-Hackers <pgsql-hackers(at)postgresql(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>
Subject: Re: Advice on MyXactMade* flags, MyLastRecPtr, pendingDeletes and lazy XID assignment
Date: 2007-08-29 19:20:29
Message-ID: 8737.1188415229@sss.pgh.pa.us
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"Florian G. Pflug" <fgp(at)phlo(dot)org> writes:
> Tom Lane wrote:
>> One thought here is that it's not clear that we really need a concept of
>> transaction-controlled vs not-transaction-controlled xlog records
>> anymore.

> I've thinking about keeping XLOG_NO_TRAN, and doing
> if (!no_tran)
> Assert(TransactionIdIsValid(GetCurrentTransactionIdIfAny())
> in xlog.c as a safety measure.

Why do you think this is a safety measure? All that it is checking
is whether the caller has preserved an entirely useless distinction.
The real correctness property is that you can't write your XID
into a heap tuple or XLOG record if you haven't acquired an XID,
but that seems nearly tautological.

regards, tom lane

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